Conductive Pillar Structure for Low-Resistivity LED Modules
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Solution Overview
Problem
Current copper pillar bump structures in flip-chip packaging for light-emitting devices require complex and costly processes due to the use of a tin-plated layer on a copper-plated layer, necessitating an improvement for better performance and lower packaging costs.
Innovation Solution
A light-emitting module and device design featuring conductive pillars with a copper core and a tin-silver alloy, along with internal and external pads, to enhance electron mobility and reduce resistivity, utilizing a substrate with through holes for pillar placement and separate sub-pads for improved electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tin-plated layer is plated on a copper-plated layer in copper pillar bumps, then the electrical connection performance is improved, but the manufacturing process complexity and cost increase
Solution Approach 1:
The patent extracts the tin-plating process from the copper pillar bump structure, retaining only the copper pillar without the additional tin-plated layer. This simplifies the manufacturing process while maintaining acceptable electrical connection performance through the copper pillar and solder joint combination.
Solution Approach 2:
The patent uses a simpler copper pillar structure that can be directly soldered, replacing the more complex and expensive tin-plated copper pillar. This approach uses readily available copper materials and simpler processing, reducing overall manufacturing cost and complexity.
2Reliability
If a tin-plated layer is plated on a copper-plated layer in copper pillar bumps, then the electrical connection performance is improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes the expensive tin-plating process from the copper pillar bump structure, keeping only the copper pillar. This extraction eliminates the additional material and processing costs associated with tin plating while maintaining functional electrical connection through alternative design approaches.
Solution Approach 2:
The patent adopts a cost-effective copper pillar design that can be directly soldered without expensive tin plating. This approach uses economical copper materials and simpler manufacturing steps, significantly reducing the overall manufacturing cost while achieving acceptable reliability.
3Reliability
If conductive pillars with copper core and tin-silver alloy are used, then electron mobility and electrical conductivity are improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent employs a composite structure with a copper core and tin-silver alloy outer layer in the conductive pillar. This composite design combines the high electrical conductivity of copper with the beneficial properties of tin-silver alloy, achieving superior electron mobility while managing manufacturing complexity through integrated processing.
Data Source
AI summary
A light-emitting module and a light-emitting device are provided. The light-emitting module includes a substrate, a conductive pillar, an internal pad, a light-emitting element, and an external pad. The conductive pillar is disposed in a through hole of the substrate and includes first, second, and third portions. The first portion includes a first metal. The second and third portions are respectively connected to two ends of the first portion. The second and third portions include an alloy. The alloy includes a second metal and a third metal different from the first metal. The internal pad is connected to the second portion of the conductive pillar and electrically connected to the light-emitting element. The external pad is connected to the third portion of the conductive pillar. The conductive pillar, having high electron mobility, may reduce resistivity more effectively, thereby improving the performance of the light-emitting device and the light-emitting module thereof.